Technology, Investment, and Economic Fluctuations

Since 1854, the United States has experienced 32 business cycles. While the average length of these cycles (trough-to-trough) has been 51 months, there has been significant variation across different subperiods. This paper attempts to explore the relationship between capital accumulation, technology accumulation, and the business cycle.

7. Bericht über den Neureuther Alpenpflanzengarten : erstellt von der Alpenverein-Sektion Tegernsee

anonym

Forma móvil: Intermission 6, de Morton Feldman

Fil: Solare, Juan María.

Isotope composition of dolomite, calcite and pore-waters of ODP Leg 210 samples

Early diagenetic dolomite beds were sampled during the Ocean Drilling Programme (ODP) Leg 201 at four reoccupied ODP Leg 112 sites on the Peru continental margin (Sites 1227/684, 1228/680, 1229/681 and 1230/685) and analysed for petrography, mineralogy, d13C, d18O and 87Sr/86Sr values. The results are compared with the chemistry, and d13C and 87Sr/86Sr values of the associated porewater. Petrographic relationships indicate that dolomite forms as a primary precipitate in porous diatom ooze and siliciclastic sediment and is not replacing the small amounts of precursor carbonate. Dolomite precipitation often pre-dates the formation of framboidal pyrite. Most dolomite layers show 87Sr/86Sr-ratios similar to the composition of Quaternary seawater and do not indicate a contribution from the hypersaline brine, which is present at a greater burial depth. Also, the d13C values of the dolomite are not in equilibrium with the d13C values of the dissolved inorganic carbon in the associated modern porewater. Both petrography and 87Sr/86Sr ratios suggest a shallow depth of dolomite formation in the uppermost sediment (<30 m below the seafloor). A significant depletion in the dissolved Mg and Ca in the porewater constrains the present site of dolomite precipitation, which co-occurs with a sharp increase in alkalinity and microbial cell concentration at the sulphate-methane interface. It has been hypothesized that microbial 'hot-spots', such as the sulphate-methane interface, may act as focused sites of dolomite precipitation. Varying d13C values from -15 per mil to +15 per mil for the dolomite are consistent with precipitation at a dynamic sulphate-methane interface, where d13C of the dissolved inorganic carbon would likewise be variable. A dynamic deep biosphere with upward and downward migration of the sulphate-methane interface can be simulated using a simple numerical diffusion model for sulphate concentration in a sedimentary sequence with variable input of organic matter. Thus, the study of dolomite layers in ancient organic carbon-rich sedimentary sequences can provide a useful window into the palaeo-dynamics of the deep biosphere.

Horizontal profiles of longwave and shortwave radiation components over sea ice near Barrow, Alaska during the 2011 melt

An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.

Stable oxygen isotopes of Globigerinoides ruber and biostratigraphic datums at ODP Site 165-1002

Ocean Drilling Program Site 1002 in the Cariaco Basin was drilled in the final two days of Leg 165 with only a short transit remaining to the final port of San Juan, Puerto Rico. Because of severe time constraints, cores from only the first of the three long replicate holes (Hole 1002C) were opened at sea for visual description, and the shipboard sampling was restricted to the biostratigraphic examination of core catchers. The limited sampling and general scarcity of biostratigraphic datums within the late Quaternary interval covered by this greatly expanded hemipelagic sequence resulted in a very poorly defined age model for Site 1002 as reported in the Leg 165 Initial Reports volume of the Proceedings of the Ocean Drilling Program. Here, we present for the first time a new integrated stratigraphy for Site 1002 based on the standard of late Quaternary oxygen-isotope variations linked to a suite of refined biostratigraphic datums. These new data show that the sediment sequence recovered by Leg 165 in the Cariaco Basin is continuous and spans the time interval from 0 to ~580 ka, with a basal age roughly twice as old as initially suspected from the tentative shipboard identification of a single biostratigraphic datum. Lithologic subunits recognized at Site 1002 are here tied into this new stratigraphic framework, and temporal variations in major sediment components are reported. The biogenic carbonate, opal, and organic carbon contents of sediments in the Cariaco Basin tend to be high during interglacials, whereas the terrigenous contents of the sediments increase during glacials. Glacioeustatic variations in sea level are likely to exert a dominant control on these first-order variations in lithology, with glacial surface productivity and the nutrient content of waters in the Cariaco Basin affected by shoaling glacial sill depths, and glacial terrigenous inputs affected by narrowing of the inner shelf and increased proximity of direct riverine sources during sea-level lowstands.